Well, in many of these fanfictions, the theme of magical discovery together is quite popular. They both are mages in Fairy Tail, so authors like to write about them finding new spells or magical artifacts while also strengthening their bond. And then there's the theme of protecting each other. Natsu is a very protective character, and in fanfictions with Lisanna, this trait is often emphasized as he defends her from various threats. Lastly, the theme of family acceptance can be seen. Since the Fairy Tail guild is like a family, fanfictions might explore how the other guild members react to their relationship and how Natsu and Lisanna deal with it.
In such fanfictions, the theme of emotional healing is often present. Given their past traumas in the series, like Lisanna's supposed death and Natsu's own orphan past, fanfictions may focus on how they heal each other's emotional wounds. Another popular theme is the celebration of their differences. Natsu is hot - headed and impulsive, while Lisanna is more gentle and nurturing. Fanfictions play with these differences and show how they complement each other. Also, the theme of shared dreams can be found. Maybe they both dream of a more peaceful Fairy Tail world or of achieving a certain level of magic power together.
One popular storyline is where Natsu and Lisanna go on an adventure together to find a long - lost magical artifact. This adventure tests their relationship and their individual strengths. Another is a story where they have to team up to save the Fairy Tail guild from a powerful enemy. It often involves them using their unique magic skills in creative ways.
Writers often develop Natsu by showing his growth in understanding his feelings for Lisanna. In the original series, he's more focused on adventures and friends in a general sense. But in fanfictions, he might start to realize his deeper romantic feelings for Lisanna. For Lisanna, her development could be in becoming more assertive in her relationship with Natsu. She might not be as passive as she sometimes seems in the original story.
In many fanfictions, their relationship is often characterized by a deep loyalty. Natsu is always there to protect Lisanna, and Lisanna is a source of support for Natsu. For example, in some stories, when Natsu gets into a tough fight, Lisanna is the one who heals his wounds and gives him the motivation to keep going.
Another idea in fanfiction could be a 'what if' scenario. What if Lisanna never 'died'? In this case, their love could have blossomed earlier. They might have been a couple throughout the main series, and fanfictions could explore how that would have changed the dynamics between Natsu and the other characters like Lucy.
One great fanfiction is 'Natsu and Lisanna's Adventure'. It beautifully portrays their relationship development. It starts with a simple quest they embark on together, and as they face challenges, their bond deepens. The author does a wonderful job of showing Natsu's protective side towards Lisanna and Lisanna's admiration for Natsu.
One common theme might be a 'what - if' scenario where Natsu and Wendy have a closer relationship than in the original series. But since 'lemon' implies mature content, it's not really in line with the general Fairy Tail spirit. The original series is more about magic, friendship, and guild loyalty.
Some common themes are redemption and forgiveness. Given Zeref's actions in the original Fairy Tail series, fanfictions might delve into whether Natsu could be the one to bring about Zeref's redemption. Family also plays a role. With their shared history, fan stories could explore the idea of them being part of an unexpected family or having a brotherly bond in a different way than what's shown in the official story.
One popular theme could be adventure. Since 'Fairy Tail' is an adventure - filled series, fanfictions might continue that trend with Natsu and Erza going on new quests together. Another theme could be friendship development. Despite the 'lemon' aspect which might imply a romantic or more adult - like relationship, many fanfictions also focus on how their friendship grows deeper. Also, the theme of self - discovery can be present as they face various challenges and learn more about themselves.
In some fanfictions, Natsu might save Lisanna from a powerful dark wizard. He could use his Fire Dragon Slayer magic to overpower the enemy and rescue her.
The popularity might be due to the character of Natsu. He is a very dynamic and popular character in the Fairy Tail series. Fans love to explore different scenarios and relationships involving him.